The investigators propose to develop microdevices for the specific chemical analysis of multiple metabolites in small sample volumes of biological fluids. The specificity and sensitivity is provided by specific reactions that couple analytes to bioluminescent-based enzyme reactions and produce light proportional to the analyte concentration. Bioluminescent analytical assays, in a miniaturized and stable format, can measure sub-microMolar concentrations in microliter sample volumes. The goal of the first phase (R21) is to engineer microfluidic structures, develop enzyme packaging and stabilization techniques, and optimize optical detection systems in order to measure two model analyte solutions (galactose and lactate) using bioluminescent reactions. The goal of the second phase (R33) is to implement other bioluminescent assays in the microfluidic detection system, develop specific diagnostic panels, utilize practical biofluid samples and enhance analytical accuracy and precision. The proposed Micro-Analytical System (microAS) will be convenient to operate in point-of-care (POC) and home environments. It will likely evolve to measure up to 100 different metabolites in the submicroMolar to milliMolar range from one 1-100 microL biofluid sample, and include customized comprehensive diagnostic panels for basic research, clinical research, and for personal disease and health management. These systems would provide rapid results, facilitate patient empowerment, and reduce health care costs.